Setting, grinding, and balancing machine



June 9,. 1925 1,541,370

L. T. MEDHOLDT SETTING, GRINDING, AND BALANCING MACHINE 3 Shee Filed Oct. 8, 1923 l June 9, 1925.

| T. MEDHQLDT SETTING, GRINDING, AND BALANCING MACHINE with Filed Oct. 8

' June 9, 1925.

L. T. MEDHOLDT SETTING, GRINDING, AND BALANCING MACHINE 3 S he'ets-Sheet 5 Filed Oct 8, 1923 i v r dune ti rrnur LOUIS T. TqiTrDHQLDT, GE WINTHROP, BEASSACHUSETTS, ASSIGNOB TO H. C. DODGE GQMPANY, or scorn eos'ron, nassacnnsnrrs, a

conronarroii or raAssaci-IU- SETTING, GRINDING, AND BALAN (31151" G MACHINE.

Application filed Gctober 8, 1923. SerialNc. 561237.

To all whom it may concern:

Be it known that 1, Louis 1. M coironn'r, a citizen of the United States, and'a resident of lVinthrop, in the county of Suii'olk and State of Massachusetts, have invented an Improvement in Setting, Grinding, and Balancing Machines, of which the following description, in connection with the accompanying drawings, is a specification, like numerals on the drawings representing like parts.

My present invention relates to setting and grinding machines, and more particu larly to an improved combined balancing,

setting and grinding machine for grinding to any desired shape or contour detachably mounted knives in a-revolub-le cutter head.

In modern types of wood working machines, a revolving cuttter head is employed in which a plurality of cutting knives are detachably mounted. In order to do good work with modern type oi wood working machine, it is necessary and practically essential that the knives be properly set and t 1e cutter head, speaking of such cutter head as a unit, must be accurately balanced and the various cutting knives ground with keen edges. lVithout the use of proper equip ment, it is practically impossible to set the so detachably mounted knives in the cutter head and grind or dress the cuttingknives to an accurate angle and with keen edges. lIo equipment or" this kind as a unitary device is at present available as far as I am aware. Unless the cutter head is in pro-per balance, the high speed at which it must necessarily revolve to do the work required of it is sufiicient to cause the production of poor work with its attendant necessary high wastage.

In my present invent-ion I have devised a machine that sets theknivcs on any detachable type of cutter head in a true radial circle by a method which utilizes the human senses of touch and sight, which are considered to be the most dependable elements employed in mechanics .for correcting inaccuracies. Further, my improved device will permit the grindingof straight, milled, or

circular cutters at any desired clearance or cutting bevels and without removing them from the cutter. In practicing my improved invention, I provide a yoke that pports the gr n er which is eas l and quic ly swivelled to permit angular grinding on the sides or ends or" the knives nection with my device, I provide an im-. proved vmeans for balancing up the cutter heads, which feature of construction consists in a plurality of metallic sensitive discs or rollers mounted in precision bearings.

My improved device is also portable, thereby permitting its use at any convenient place in a mill on a bench or table and can be equipped with any-diameter spindle for any desired bore in the cutter heads. The grinding wheel is directly connected to an electric motor which may be quickly connected to any standard electric lighting socket and the spindle for holdingthe cutter heads can be utilized toaccommodate any type of detachable cutter head, whether round, square, or otherwise, and is also applicable for cutter heads used for matching, molding, tenoning, coping, grooving, dovetailing, or other special cuts or types.

' Variousother features of the novel construction and arrangement of parts will appear as the description of the invention progresses.

In the accompanying drawings illustrating the preferred embodiment of my invention,

Fig. 1 is a plan view;

Fig. 2 is a rear elevation;

Fig. 3 is a side elevation;

Fig. 4: is anend elevation of the right hand portion of 'Fig. 1;

vFig. 5 is a sectional elevation on the line 5+5 of Fig. 3; I

Fig. 6 is a detail of the grinding wheel and a portion of the cutter head illustrating l 0 wer the position of the grinding wheel when grinding the throat of a cutter, and

Fig. '4' is a detail view showing a method of grinding the clearance bevel on a cutter.

Referring to the drawings, 10 designates a base or platform 10 having formed integral therewith and extending upwardly therefrom at either side of one end side p t s 11 a d re pective y h ide plate 11 has formed integral therewith on the inner face thereof and near its lower end a boss 13 threaded to receive a bearing screw 14 which is provided with a knurled head 15 on its outer end and with a locking nut 16 and by means of which the bearing screw 14 may be adjustably secured in the side plate. The side plate 12 has formed integral therewith and on the inner face there of near its lower end a boss 17 provided with a perforation threaded to receive a bearing screw 18 that is in. alincment with a bearing screw 14 in the side plate 11. The bearing screw 18 is provided with a knurled head 19 and with a nut 20 and by means of which the bearing screw 18 may be adjustably secured in the side plate 12.

The numerals 21 and 22 designate members-spaced apart by, and secured to, a rod or shaft 23, as clearly shown in Fig. 2. The

- members 21 and 22 are in alinement with each other and at their bottom ends are provided with recessed bearings adapted to be engaged by the bearing screws 14 and 18 so that the frame comprised of the members 21 and 22 and shaft 23 is rotatable about the bearings 14 and 18 as a center. The shaft 23 is reduced and threaded, as indicated at 24, such thread ed reduced end passing through an arcuate slot 25 in the side plate 12 and screwing onto such threadedend 18 is a thumb nut 26. The end of the shaft 23 remote from the threaded portion 24 is reduced in diameter, as indicated at 27 and this reduced end works in an arcuate slot 28 formed in a boss or enlargement on the inner face of the plate Hand held in the arcuate slot 28 in engagement with the reduced end 27 by a threaded member 30 is a coil spring 31 and it will be obvious that such coil spring tends to move the frame comprised of the members 21 and 22 and shaft 23 to the right, as viewed in Fig. 3. The side plate 11 has formed integral therewith a member 32 through which is threaded a thumb screw 33, the inner end of this thumb screw engaging with the reduced end 27 of the shaft 23 and by means of which a relatively fine adjustment to the movement of the shaft 23 may be given. The side plate 11 is formed with an arcuate slot 34, it being understood that the arcuate slots 28 and 34 have as a center the pivot screw 14. The member 21 has formed integral therewith and extending outward laterally therefrom an ear or lug 35 that engages the inner surface of the member 11, as clearly shown in Fig. 5, and passing through a perforation in the ear 35 is a bolt 36 which also passes through the arcuate slot 34 and is provided on its outer threaded end with a thumb nut 37. In order to allow the assembling of the bolt 36 in the lug 35, the member 21 is provided with a perforation 38, as clearly shown in Fig. 5.- When it is desired to adjust the frame comprised of the members 21 and 22 and the shaft 23 about the pivot bearings 14 and 18, the thumb nuts 26 and 37 are loosened and the thumb screw 36 is moved relative to the lug 32 to cause a movement of the frame comprised of such members 21 and 22 and shaft 23 by means of such screw engagingwith the reduced end 27 of the shaft 23. hen the desired point is reached, the thumb nuts 26 and 37 are screwed onto their respective cooperating members to firmly hold the framework in adjusted position.

Extending laterally outward and forward from the members 21 and 22 and formed integral th rewith are cars 39 and 40 respectively provided with perforations that are in alinement with each other and adapted to receive the ends of a shaft 41, such shaft being pinned or screwed to the ears 3'9 and I? 40 and lies parallel with the shaft 23. Slidably mounted on the shaft 41 are collars 42, each being provided with a wing screw 43 and by means of which the collars may be secured to the shaft 41 in any position along 4 the length thereof.

The upper ends of each of the members 21 and 22 are perforated and provide bearings in which is slidable a shaft 44, said shaft 44 lying parallel with the shaft 23 and 41. Secured to the shaft 44 intermediate its ends by set screws, pins, or in any other suitable manner, is a motor base or cradle 45 and secured to the boss or cradle is an electric motor 46, the securing means being preferably a flexible metallic strap 47 provided at each end with a threaded member 147 which extends-through a perforation in the base or cradle and is provided with a nut 48. The shaft 49 of the motor 46 has secured thereto in any suitable manner a wheel 50 of any suitable abrasive material. Secured to the shaft 44 adjacent the base or cradle 45 is a member 51, the lower end of which is provided with a semi-cylindrical recess (not shown that engages with, and partially surrounds, the shaft 43, the mem ber 51 acting as a steadying means for the shaft 44 and elements carried thereby and prevents rotation of the shaft 44.

The base or platform 10 forwardly of the mechanism above described is provided with a centrally located perforation that forms a bearing for a member 52 formed integral with, or secured to, the under face of a member 53. Formed in the member 53 about the member 52 as a center are arouate slots 54 through which pass the threaded ends of bolts 55, which bolts extend upwardly through perforations in the base 10, and fitting onto the threaded ends of such bolts are nuts 56, this means being employed to hold the member 53 in fixed position with relation to the base 10. Formed integral with the member 53 on opposite sides Lil thereof and symmetrically disposed to the member 52 are standards or uprights 57 each provided with a V slot 58 forming an open bearing member for the reduced ends 59 of a cutter holding shaft 60. Each of the members 57 on either side of the open bearing slot 58 is provided with lugs 61 and each of the lugs 61 is provided with a vertically arranged perforation 62 in which is slidably mounted a gauge holder 63. Also, Each lug 61 is threaded to receive a set screw 64 and to each of the set screws is pivotally attached a handle 65 and by means of which the set screws may be operated. The gauge holder (33 is provided with a transverse pe foration at its upper end and with a slot 66 extending from the top of the holder downward into such perforation, a screw 166 being employed to clamp the ends of the member 63 together. This construction forms practically a spring fork at thetop of each of the gauge holders 63, and fitting into the transverse perforations is a shaft 67 to one end of which is secured an arm 68 drilled at its outer free end to receive a gauge point 69. The outer free end is slitted, as shown at 70 in Fig. 1, and a screw 71 en ables the slitted end to be forced together to firmly fasten the gauge point 69 in psition.

The gauge point 69 is adapted to engage, with a cutter blade 72 secured in a cutter head 73 by means of a screw or plurality of screws 74, as is usual in cutter heads of this type. The shaft 60 may be of any suitable diameter to receive the cutter head 73 of any desired bore, my invention being applicable for the grinding of cutters 73 attached to any sized cutter head.

Secured to the forward end of the base and on each side thereof by bolts 75 are bearing members 76, in each of which are rotatably mounted on anti-friction bearings (not shown) parallelly arranged shafts 77 and to each shaft is secured a circular disc 78 of ground and hardened steel It will be noted by reference 2, Fig. 3, that the shafts 7 7 are so arranged, and the discs 78 are of such diameter, that there is formed a substantially V shaped depression 79' in which may fit the reduced end 59 of the shaft 60. In cutter heads of the type adapted to be worked upon by the present invention. it is essential, because of the extremely high speed at which such, cutter heads are rotated, that the said cutter heads be perfectly balanced and in order to em ploy a ready means for balancing up such cutter heads, the device comprised of the rotatably mounted discs 78 has been devised. Such discs 78 being secured to, and rotatable with, shafts 77 mounted in antifriction rollers, there is formed with each pair of discs 78 an extremely sensitive bearing and when a shaft 60. on which a cutter head 73 is mounted, is placed in the bearings formed by cooperating discs 78, the slightest excess of weight on one of the other side of the center of the shaft 60 would cause a rotative-movement of the said shaft. Such excess weight may be readily removed by ordinary means well known to those skilled in this art and my device forms a structure in which the unbalance in a. cutter head may be quickly and readily remedied.

The operation of my improved apparatus is as follows, it being assumed that is desired to balance, set,.and grind cutters'in a rotatably mounted cutter head. A shaft 62 of appropriate diameter has mounted thereon a cutter head 73 in which is secured, by the bolts 72, a plurality of cutter blades 72. The shaft 60 containing the cutter head 73 and attached cut-tor blades 72 is placed in the V slots 58 and wing screws 43 loosened to move the cylindrical'members 42 into position to engage with the cutter blades 72. If necessary, the frame members comprised of the members 21 and 22 and shaft 23 is rotated about its pivot point to bring the cylindrical members 42 into engaging position with the cutter blades 72. The cutter blades 72 are brought successively into engagement with the cylindrical members 42 and the bolts 74 utilized to securely clamp the cutter blades in position. Afterthe setting operation, the shaft 60 with the cutter head 7 3 thereon is transferred to the rotatably mounted discs 78 where, by successively bringing the shaft 60 into various angular positions and momentarily leaving the same therein, any unbalance in the cutter head and attached cutter blades will become apparent, due to the turning movement produced by such overbalance and the overbalance may be readily eliminated by shifting the position of appropriate cutter blade 72 with respect to the cutter head 7 After the balancing operation, the shaft 60 with attached cutter head 73 has its reduced ends 59 placed in the V slots 58 and the gauge point 69 is brought into position to engage with the angle made by a cutter blade 72 and the cutter head 73, as clearly shown in Fig. It is assumed that the cutting edges of the: cutter blades 72 are to lie in the surface, of a true cylinder and, therefore, that the shaft 60 is to lie parallel with the shaft 44. If necessary, therefore, the nut 56 is backed off from the screws and the table 53 rotated about 52 as a center until the axis of the shaft is parallel with the axis of the shaft 44, after which the nuts 56 are tightened up on the screws 55 tohold such table or platform 53 rigidly in position with respect to the base or platform 10. It is usual to grind the clearance of a cutter, such as 72, first and, therefore, the frame comprised of the members 21 and 22 and shaft 23 is swung about its pivot bearings 14 and 18 until the bevel on the abrasive wheel is in proper position with respect to the cutter 72 to grind the clearance of the proper angle thereon, as clearly shown in Fig. 3, the gauge point 69 being also moved to assist in obtaining the proper angle between the cutters 73 and the abrasive wheel 50. When the proper angle is reached, the frame referred to and the gauge point 69 are securely fastened in position and, power being thrown onto the motor 46, the operator moves the motor across the length of the cutter 72, the member 51 sliding on the-shaft 53 and the shaft a l sliding in the members 21 and 22 during this movement. As the grinding of the clearance on the cutters 72 progresses, the shaft with attached cutter head is transferred to the balancing wheel 78 and the cutter head again tested for balance. After the completion of the grinding of the clearance on the cutters, the throat of such cutters is ground and the frame comprised of the members 21 and 22 and shaft 23 is rotated on the pivot bearings 14: and 18 to bring the abrasive wheel 50 into engagement with the throat of the cutter, as shown in Fig. 6 and where the grinding of such throatpro'ceeds in the usual manner.

If the cutter head 73 has the cutter 72 ground thereon at an angle, the different sized cylindrical discs 42 are employed and the platform 53 is rotated about the member 52 as a center until the appropriate angle of the shaft 60 with respect to the shaft i l is reached and the balancing, setting, and grinding operation proceeds exactly as outlined above.

In Fig. 7 is shown so much of a machine as illustrates one method, other than that above described, for grinding the clearance bevel on a cutter, as 72, held in the cutter head 73. In this construction, the cutter head 73 is mounted on the shaft 60 so as to bring that portion of the cutter 72 on which the clearance is to be ground against the face of the abrasive wheel 50 that is mounted on the shaft 49 of the motor l6. The gauge point 69 is carried by the member 68 and engages with the edge of the cutter 7 2. In this construction, the grinding is all done by the, face of the abrasive wheel 50.

A cutter balanced, set, and ground as above described willbe found to be in perfc'ct balance, regardless of the speed of rotation of same, and the balancing, setting, and grinding may be done in a minimum of time and by relatively unskilled labor.

\Vhile I have necessarily shown and described the preferred embodiment of my in vention somewhat in detail, it is to be understood that I may vary the size, shape, and arrangement of parts within wide limits without departing from the spirit of the invention.

Having thus described my invention, what I claim as new is:

1. An improved knife grinding machine for rinding a plurality of knives mounted in a cutter head, comprising a base, a pivotally frame thereon, a member slidably mounted in said frame and transversely of the base, a rotatable abrasive wheel carried on said member, and means for mounting a cutter head on'said frame in operative relation to the abrasive wheel.

2. An improved knife grinding machine for grinding a plurality of knives mounted in a cutter head, comprising a base, a pivotally mounted frame thereon, a memberslidably mounted in said frame and transversely of the base, a rotatable abrasive wheel carried on said member, means for mounting the cutter head on said frame in operative relation to the abrasive wheel, and means for holding the cutter head against rotation.

3. An improved cutter conditioning ma chine comprising a base, a pivotally mounted frame thereon, means for holding the frame in adjusted position, a member slidably mounted in said frame and transversely of the base, a rotable abrasive wheel, opposed bearings on said frame for holding a cutter head mounted on an arbor, means for adjusting said opposed hearings to vary the angular position of the arbor and slidably mounted member, and means for'holding the cutter head against rotation during the grinding operation.

In testimony whereof, I have signed my name to this specification.

LOUIS T. MEDHOLDT. 

